1. Field of the Invention
The present invention relates to a process and apparatus for treating a solid waste slurry formed from solid waste particles mixed with a liquid.
2. Description of the Prior Art
Increased environmental awareness has resulted in more stringent laws regulating the disposal of various kinds of waste. For instance, numerous laws have been enacted both at the federal and state levels (as well as in many countries throughout the world) regulating the disposal of solid waste generated by many different types of industry.
One industry in particular that has had to deal with solid waste and the disposal thereof is the electric utility and power generation industry. Large quantities of solid waste are created during the power generation process, particularly in power generation processes utilizing fossil fuels, such as coal. One of the known ways for the electric utility and power generation industry to deal with such solid waste is to employ sedimentation ponds wherein a solid waste is deposited within the sedimentation ponds and allowed to settle over an extended period of time. The solid portion is then withdrawn and relocated to a suitable disposal site. However, the more stringent laws regulating the disposal of solid waste have made it more difficult for the electric utility and power generation industry to continue employing such disposal techniques. Still, there are numerous existing sedimentation ponds, and the use of such a technique by the electric utility and power generation industry continues to serve as a temporary solution to the solid waste disposal problem that ultimately must be addressed. Of course, the problem of eventually dealing with solid waste contained in sedimentation ponds is further complicated by the solid waste's admixture with the water contained in the sedimentation pond. Prior to properly disposing of the solid waste, it is necessary to remove or separate the solid waste from the water.
There do exist techniques for the treatment or processing of a water or slurry having solid waste materials admixed therewith. For example, generally known are waste water treatment facilities, such as those used by municipalities, that employ, among other equipment, centrifuges, thickeners, and water clarifiers. However, such facilities require large capital investments and include high operating expenses.
U.S. Pat. No. 3,788,469 discloses a process for removing ash generated during a power generation process from the precipitators. This process provides for removing fuel ash from the precipitator bottoms by circulating water through the bottoms of the precipitators to carry off the ash and then employing hydrocyclone separation to produce a major overflow fraction of reduced solids content and a minor overflow fraction of increased solids content.
U.S. Pat. No. 4,571,301 discloses a method and apparatus for cleaning chemical water solutions. A slurry is subjected to a combination of screening, hydrocyclone separation, and media filter separation in order to separate the particulate materials from the slurry.
U.S. Pat. No. 4,039,425 discloses a method for preparing a coal slurry substantially depleted in mineral-rich particles. This method employs an elutriation step for removing the mineral-rich particles and is directed primarily toward obtaining a slurry with particles of a uniform size.
U.S. Pat. No. 4,909,950 discloses a process and apparatus for separating solid-liquid compositions. Separation is achieved by employing one or more hydrocyclones in combination with a ceramic filtering process.
U.S. Pat. No. 2,381,760 discloses an apparatus and method for supplying clarified liquid. This process includes screen separation and hydrocyclone separation. The process is particularly adaptable for clarification of sea water.
There remains a need for a process and apparatus for treatment of a solid waste slurry formed from solid waste particles mixed with a liquid that is effective, reliable, and economically feasible, particularly for industries not primarily involved with water/solid waste treatment, such as the electric utility and power generation industry.